To invert the colors of the displayed content on the OnePlus smartphone screen, we only need to navigate to the accesibility settings and enable color inversion.

Note: Color inversion reverses the entire contents of the screen, including media such as photos or videos and can result in a distorted display.

Android 10 | OxygenOS 10.0
Colour inversion -  Open the  Settings
Colour inversion -  Tap on  System
Colour inversion -  Tap on  Accessibility
Colour inversion -  Enable or disable  Color inversion
  1. Open the Settings
  2. Tap on System
  3. Tap on Accessibility
  4. Enable or disable Color inversion

OnePlus Instructions